1. Field of the Invention
This invention relates an injection mold.
2. Description of the Prior Art
A movable mold half of an injection mold for molding an article having an undercut at at least one end portion is generally provided with a slide core which defines inner surfaces of the undercut and said one end portion of the article and which is slidable relative to the other portion of the mold half in a direction at an angle to the direction in which the molded article is moved to be removed from the mold so that the slide core is moved inward away from the undercut when the injection mold is opened and the article is ejected from the movable mold half. This is for preventing interference of the molded article with the portion of the mold half defining the undercut and the end portion during ejection of the article.
However, since the undercut is formed behind the slide core, the plastic material forming the undercut and the end portion of the article is apt to bite on the slide core, thereby preventing the slide core from being smoothly removed from the article. This is especially significant when one or more projections such as a rib is defined by the slide core in addition to the undercut.
This problem may be overcome by providing the slide core with a side ejector pin which is moved laterally in response to the sliding motion of the slide core to push outward the molded article as disclosed in Japanese Pat. Publication No. 59(1984)-10298. However, this approach is disadvantageous in that the side ejector pin complicates the structure of the slide core and that the slide ejector pin can mark the molded article.